JP2020134892A - Zoom lens and image capturing device having the same - Google Patents

Abstract

To provide a zoom lens that offers a high zoom ratio and good optical properties over an entire zoom range.SOLUTION: A zoom lens provided herein consists of a first lens group having positive refractive power, a second lens group having negative refractive power, and a rear group comprising a plurality of lens groups, arranged in order from the object side to the image side, and is configured such that distances between adjacent lens groups change while zooming. A lens group of the rear group located on the most image side has positive refractive power. An imaging magnification β2w of the second lens group at the wide-angle end, an imaging magnification β2t of the second lens group at the telephoto end, a total lens length Lw at the wide-angle end, a total lens length Lt at the telephoto end, a focal length fw of the zoom lens at the wide-angle end, a focal length f1 of the first lens group, a focal length f2 of the second lens group, a focal length ft of the zoom lens at the telephoto end, a zoom ratio Z of the zoom lens from the wide angle end to the telephoto end, a zoom ratio Z2 of the second lens group from the wide-angle end to the telephoto end, and a back focus skt at the telephoto end are each set appropriately.SELECTED DRAWING: Figure 1

Description

The present invention relates to a zoom lens and an image pickup device using the same, and is particularly compact and has high performance, and is suitable as an image pickup optical system used for an image pickup device such as a digital camera or a surveillance camera.

In recent years, in an image pickup device using an image pickup device, there is an increasing demand for higher image quality and miniaturization of the entire image pickup device by increasing the size of the image pickup device. Along with this, the imaging optical system used in these imaging devices is required to be a zoom lens having a high zoom ratio and high imaging performance.

Conventionally, the entire system is a compact zoom lens with a high zoom ratio, in order from the object side to the image side, a first lens group with a positive refractive power, a second lens group with a negative refractive power, and one or more lens groups following it. A positive lead type zoom lens having a rear group including the above is known (Patent Documents 1 to 3). Patent Document 1 discloses a zoom lens including a first lens group to a fourth lens group having positive, negative, negative, and positive refractive powers in order from the object side to the image side.

Further, Patent Document 2 discloses a zoom lens composed of a first lens group to a fourth lens group having positive, negative, positive, and positive refractive powers in order from the object side to the image side.

Further, Patent Document 3 discloses a zoom lens including a first lens group to a fourth lens group having positive, negative, positive, and negative refractive powers in order from the object side to the image side.

Japanese Unexamined Patent Publication No. 2015-191061 Japanese Unexamined Patent Publication No. 2015-169931 Japanese Unexamined Patent Publication No. 2-181716

It is relatively easy to achieve a high zoom ratio while reducing the size of the entire positive lead type zoom lens. Many positive lead type zoom lenses are required to have high optical performance over the entire zoom range while reducing the size of the entire system. Further, an image sensor such as a CCD sensor or a CMOS sensor has a sensor incident angle characteristic of a luminous flux, and when light having a large incident angle enters, shading occurs and the image quality deteriorates.

Therefore, it is strongly required to reduce the angle of incidence of the luminous flux on the image sensor and prevent deterioration of image quality due to shading or the like. In order to obtain a zoom lens that satisfies these requirements, the zoom type (the number of lens groups and the sign of the refractive power of each lens group), the refractive power of each lens group constituting the zoom lens, and their zooming It is important to set the movement conditions appropriately. For example, in a positive lead type zoom lens, the aberration generated in the front lens group is magnified by the rear lens group. Therefore, it is important to appropriately set the lens configuration of the front lens group and the rear lens group.

An object of the present invention is to provide a zoom lens capable of obtaining good optical characteristics over the entire zoom range at a high zoom ratio and an image pickup apparatus having the same.

The zoom lens of the present invention comprises a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group having a plurality of lens groups arranged in order from the object side to the image side.
In a zoom lens where the distance between adjacent lens groups changes during zooming
The lens group on the most image side of the rear group has a positive refractive power and has a positive refractive power.
The imaging magnification of the second lens group at the wide-angle end at infinity focusing is β2w, and the imaging magnification of the second lens group at the telephoto end at infinity focusing is β2t.
The total length of the lens at the wide-angle end is Lw, the total length of the lens at the telephoto end is Lt, the focal length of the zoom lens at the wide-angle end is fw, the focal length of the first lens group is f1, and the second lens group is in focus at infinity. The focal length is f2, the focal length of the zoom lens at the telephoto end is ft, the magnification ratio of the zoom lens from the wide-angle end to the telephoto end is Z, and the magnification ratio of the zoom lens is Z, and the infinity of the second lens group from the wide-angle end to the telephoto end. The magnification ratio at the time of focusing is Z2, and the back focus at the telephoto end is skt.
Z = ft / fw for Z and Z2
Z2 = β2t / β2w
When
0.5 <Lw / fw <4.0
-5.5 <f1 / f2 <-2.0
1.7 <Z / Z2 <3.0
0.0 <skt / Lt <0.2
It is characterized by satisfying the conditional expression.

In addition, the zoom lens of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a negative refractive power arranged in order from the object side to the image side. Consists of a rear group with a lens group of
In a zoom lens where the distance between adjacent lens groups changes during zooming
The lens group on the most image side of the rear group has a positive refractive power and has a positive refractive power.
The imaging magnification of the second lens group at the wide-angle end at infinity focus is β2w, the imaging magnification of the second lens group at the telephoto end at infinity focusing is β2t, and the imaging magnification of the third lens group at the wide-angle end is β2t. The magnification is β3w, and the imaging magnification of the third lens group at the telephoto end is β3t.
The total length of the lens at the wide-angle end is Lw, the total length of the lens at the telephoto end is Lt, the focal distance of the zoom lens at the wide-angle end is fw, the focal distance of the first lens group is f1, and the second lens group and the first lens group at the wide-angle end. The combined focal distance of the three lens groups at infinity is f23, the focal distance of the zoom lens at the telephoto end is ft, the magnification ratio of the zoom lens from the wide-angle end to the telephoto end is Z, and the telephoto end is telephoto. The magnification ratio of the second lens group at infinity focusing toward the end is Z2, the magnification ratio of the third lens group at infinity focusing from the wide-angle end to the telephoto end is Z3, and the back at the telephoto end. Focus on skt
Z = ft / fw
Z2 = β2t / β2w
Z3 = β3t / β3w
Z23 = Z2 x Z3
When
0.5 <Lw / fw <4.0
-5.5 <f1 / f23 <-2.0
1.7 <Z / Z23 <3.0
0.0 <skt / Lt <0.2
It is characterized by satisfying the conditional expression.

According to the present invention, a zoom lens having a high zoom ratio and good optical characteristics over the entire zoom range can be obtained.

FIG. 5 is an optical cross-sectional view of Example 1. (A), (B), (C) Aberration diagram at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of Example 1. FIG. 5 is an optical cross-sectional view of Example 2. (A), (B), (C) Aberration diagram at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of Example 2. FIG. 5 is an optical cross-sectional view of Example 3. (A), (B), (C) Aberration diagram at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of Example 3. FIG. 5 is an optical cross-sectional view of Example 4. (A), (B), (C) Aberration diagram at the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of Example 4. Schematic diagram of the image pickup apparatus of the present invention

Hereinafter, the zoom lens of the present invention and an imaging device having the same will be described.

The zoom lens of the present invention comprises a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group having a plurality of lens groups arranged in order from the object side to the image side, and is used for zooming. The distance between adjacent lens groups changes.

In addition, the zoom lens of the present invention includes a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a third lens group having a negative refractive power arranged in order from the object side to the image side. It consists of a rear group having the same lens group, and the distance between adjacent lens groups changes during zooming.

FIG. 1 is a cross-sectional view of the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens of the first embodiment. 2 (A), (B), and (C) are aberration diagrams of the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of the first embodiment, respectively. The first embodiment is a zoom lens having a zoom ratio of 2.75 and an F number of 3.61 to 4.12.

FIG. 3 is a cross-sectional view of the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens of the second embodiment. 4 (A), (B), and (C) are aberration diagrams of the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of the second embodiment, respectively. The second embodiment is a zoom lens having a zoom ratio of 2.36 and an F number of 2.88 to 3.61.

FIG. 5 is a cross-sectional view of the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens of the third embodiment. 6 (A), (B), and (C) are aberration diagrams of the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of the third embodiment, respectively. Example 3 is a zoom lens having a zoom ratio of 2.36 and an F number of 2.88 to 3.61.

FIG. 7 is a cross-sectional view of the wide-angle end, intermediate zoom position, and telephoto end of the zoom lens of the fourth embodiment. 8 (A), (B), and (C) are aberration diagrams of the wide-angle end, the intermediate zoom position, and the telephoto end of the zoom lens of the fourth embodiment, respectively. The fourth embodiment is a zoom lens having a zoom ratio of 4.10 and an F number of 4.12.

FIG. 9 is a schematic view of a main part of a camera (imaging device) including the zoom lens of the present invention. The zoom lens of each embodiment is an imaging optical system used in an imaging device such as a video camera, a digital camera, and a surveillance camera. .. In the cross-sectional view of the lens, the left side is the subject side (object side) (front), and the right side is the image side (rear). In the lens cross-sectional view, L0 is a zoom lens, i is the order of the lens groups from the object side, and Bi is the i-th lens group. BR is a rear group including a plurality of lens groups.

In the lens cross-sectional views of Examples 1 and 2, B1 is a first lens group having a positive refractive power, and B2 is a second lens group having a negative refractive power. BR is a rear group having a plurality of lens groups. Bi is the i-th lens group. The rear group BR has a lens group having a positive refractive power on the most image side. Further, in the lens cross-sectional views of Examples 3 and 4, B1 is a first lens group having a positive refractive power, B2 is a second lens group having a negative refractive power, and B3 is a third lens group having a negative refractive power. .. BR is a rear group having a plurality of lens groups. Bi is the i-th lens group. The rear group BR has a lens group having a positive refractive power on the most image side.

The rear group BR of Example 1 is composed of three lens groups of positive, negative, and positive refractive power. By forming the rear group BR with three lens groups, it is easy to improve the performance and the magnification while suppressing the manufacturing sensitivity. Further, the rear group BR of Examples 2 and 3 is composed of four lens groups having positive, positive, negative, and positive refractive powers. By forming the rear group BR with four lens groups, various aberrations are satisfactorily corrected. Further, the rear group BR of Example 4 is composed of two lens groups having positive and positive refractive powers. By configuring the rear group BR with two lens groups, the structure of the lens barrel is simplified and a zoom lens resistant to manufacturing errors is obtained.

In the cross-sectional view of the lens, SP is an aperture diaphragm. In Examples 1 and 2, the aperture diaphragm SP is arranged in the third lens group B3. In Example 3, it is arranged in the fourth lens group B4. By arranging the aperture diaphragm SP in the third lens group B3 or the fourth lens group B4 in this way, the second lens group B2 and the third lens group B3 or the third lens group B3 and the fourth lens group B4 can be arranged. By arranging them in close proximity, the total optical length after the rear group BR is shortened.

This makes the zoom lens smaller. Further, since the lens group having a positive refractive power can be arranged on the object side of the aperture diaphragm SP, the aperture diaphragm SP is made smaller to make the lens barrel smaller.

In the fourth embodiment, the aperture diaphragm SP is arranged on the object side of the fourth lens group B4. By arranging in this way, flare of the intermediate image height at the wide-angle end is cut, and high performance is facilitated. Further, by moving the aperture diaphragm SP away from the image sensor, the angle of incidence on the image sensor is loosened to facilitate high image quality. Further, if the aperture diaphragm SP is arranged on the object side of the fourth lens group B4, the third lens group B3 and the aperture diaphragm SP can be moved separately. By moving in this way, flares with a low image height can be effectively cut at an intermediate zoom position, and high image quality can be easily improved.

GB is an optical block corresponding to an optical filter, a face plate, a crystal low-pass filter, an infrared cut filter, and the like. The IP is an image plane, and when used as a photographing optical system of a video camera or a digital still camera, it corresponds to an imaging surface of an imaging element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor.

Here, the definition of the lens group in each embodiment defines the lens group having the minimum configuration that moves during zooming as one lens group. In addition, a lens that focuses on a part of the lenses in the lens group is a subgroup, and a lens that is vibration-proofed by a part of the lenses in the lens group is a subgroup.

In each aberration diagram, d is the d line (wavelength 587.6 nm) and g is the g line (wavelength 435.8 nm). M is the meridional image plane and S is the sagittal image plane. Chromatic aberration of magnification is represented by the g-line. ω is a half angle of view (half the value of the imaged angle of view), and fno is an F number.

In each of the following embodiments, the wide-angle end and the telephoto end refer to the zoom positions when the variable magnification lens group is located within a movable range on the optical axis on the mechanism in the normal imaging region.

In Examples 1 and 2, when zooming from the wide-angle end to the telephoto end, the distance between the first lens group B1 and the second lens group B2 is wider at the telephoto end than at the wide-angle end, and the distance between the second lens group B2 and the rear group BR. Each lens group moves so that is narrowed.

Further, in Examples 3 and 4, when zooming from the wide-angle end to the telephoto end, the distance between the first lens group B1 and the second lens group B2 is wider at the telephoto end than at the wide-angle end. Further, each lens group moves so that the distance between the second lens group B2 and the third lens group B3 is widened and the distance between the third lens group B3 and the rear group BR is narrowed.

In the lens cross-sectional views of Examples 3 and 4, the solid arrow with respect to the third lens group B3 indicates the movement locus of each lens group in zooming from the wide-angle end to the telephoto end when focused at infinity. The dotted arrow indicates the movement trajectory in zooming from the wide-angle end to the telephoto end when the subject is in focus at a short distance.

By moving the first lens group B1 during zooming, the refractive power of the first lens group B1 can be weakened, and axial chromatic aberration and coma are satisfactorily corrected particularly at the telephoto end.

In Examples 1, 3 and 4, the lens groups other than the lens group on the image side (final lens group) are moved as shown by arrows during zooming.

Specifically, in Examples 1, 3 and 4, when zooming from the wide-angle end to the telephoto end, the lens group other than the lens group on the image side is monotonously moved to the object side as shown by the arrow. By moving the first lens group B1 to the object side, the positive refractive power of the first lens group B1 can be weakened, and spherical aberration and coma aberration are satisfactorily corrected at the telephoto end.

Further, by moving the second lens group B2 to the object side, the amount of movement of the lens group other than the final lens group to the object side is increased, and by increasing the variable magnification of the rear group BR, the size of the zoom lens is reduced. A high zoom ratio has been obtained while trying to improve the quality. If the amount of movement of the lens group other than the final lens group is large, the scaling factor can be increased even if the refractive power of the rear group BR is reduced. As a result, coma aberration, curvature of field, and the like are satisfactorily corrected.

Further, in Examples 1, 3 and 4, the final lens group is fixed to the image sensor. Since the final lens group is arranged in the vicinity of the image sensor, it is about the size of the image sensor and is very large. When such a lens group is moved, it is necessary to increase the torque of the motor. On the other hand, in the second embodiment, by moving the final lens group to the image side, the final lens group also contributes to the magnification, the refractive power of the lens groups other than the final lens group is weakened, and a high zoom ratio is facilitated.

In Examples 1 and 2, a part of the second lens group B2 is moved along the optical axis when focusing from infinity to close range. Specifically, the negative lens on the most image side of the second lens group B2 is moved to perform focusing.

Further, in Examples 3 and 4, the third lens group B3 is moved along the optical axis when focusing from infinity to close proximity. When focusing on a close-up object, the focus lens is moved toward the image side in each embodiment. However, the lens that moves during focusing is not limited to this, and if the lateral magnification of the lens during zooming does not become -1, paraxial focus can be achieved.

That is, focus can be achieved with a part of the first lens group B1, the second lens group B2, the rear group BR, and some lenses in these lens groups. However, from the viewpoint of aberration, it is preferable to have the above configuration.

In the first embodiment, the image is displaced in the direction perpendicular to the optical axis by moving the third lens group (subgroup) B3 having a positive refractive power so as to have a component in the direction perpendicular to the optical axis. As a result, the shake of the captured image when the entire zoom lens vibrates is corrected. That is, image blur correction is performed. Similarly, in the second embodiment, the subgroups from the first lens to the third lens of the second lens group B2 are integrally moved so as to have a component in the direction perpendicular to the optical axis when correcting the image blur. .. In Examples 3 and 4, the second lens group (subgroup) B2 is moved so as to have a component in the direction perpendicular to the optical axis during image blur correction.

In each embodiment, the image blur correction is performed without newly adding an optical member such as a variable apex prism or a lens group for image blur correction, thereby preventing the entire zoom lens from becoming large. There is.

In each embodiment, the lens is moved in the direction perpendicular to the optical axis to perform vibration isolation, but the movement method is such that the subgroup for image blur correction has a component in the direction perpendicular to the optical axis. If you move it to, you can correct the blur of the image. For example, if the lens barrel structure is allowed to be complicated, the subgroup may be rotated so as to have a rotation center on the optical axis to perform vibration isolation. Further, as the subgroup, in addition to the above subgroup, the first lens group B1, a plurality of lens groups, or the entire zoom lens may be moved as a subgroup for image blur correction.

In each embodiment, the first lens group B1 includes one negative lens and one or two positive lenses. As a result, spherical aberration and coma are satisfactorily corrected at the telephoto end.

The second lens group B2 includes two or three negative lenses and one positive lens. The second lens group B2 is composed of independent lenses, and the air lens between the lenses is used to satisfactorily correct the curvature of field at the wide-angle end. Further, an aspherical surface is used for the negative lens of the second lens group B2 to satisfactorily correct curvature of field and distortion, facilitating further improvement in performance.

In Examples 1 and 2, the lens on the image side of the second lens group B2 is a negative lens having a meniscus shape that is concave on the object side, and by focusing with this lens, coma aberration and curvature of field due to focusing are caused. Fluctuations are kept small.

By performing the focusing with one lens in this way, the weight of the focus lens is reduced and high-speed focusing is facilitated.

In Examples 3 and 4, the third lens group B3 is composed of one negative lens. The third lens group B3 is a focus lens group, and by focusing with this lens group, coma aberration and curvature of field due to focusing are suppressed to be small.

In each embodiment, the rear group BR is composed of two lens groups or four lens groups. The lens group on the most object side of the rear group BR has a positive refractive power. With such a configuration, the total optical length of the rear group BR is shortened and the zoom lens is miniaturized. The lens group on the image side is configured to have a positive refractive power. With such a configuration, the angle of incidence of the light beam on the image sensor is loosened to prevent deterioration of the image due to shading or the like.

In the following description, a configuration including a first lens group having a positive refractive power, a second lens group having a negative refractive power, and a rear group will be described. However, if the lens group in which the second lens group B2 and the third lens group B3 in Examples 3 and 4 are combined is considered equivalent to the second lens group B2 in Examples 1 and 2, the configuration of each lens group is the same. I can explain.

In the zoom lens of each embodiment, the negative refractive power of the second lens group B2 is weakened, the positive refractive power of the first lens group B1 is strengthened, and the distance from the rear group BR is shortened to shorten the total lens length. I am trying to. In a zoom lens in which the imaging half-angle of view ω at the wide-angle end is ω> 30 ° as in each embodiment, the variable magnification sharing of the second lens group B2 becomes small with such a configuration. For this reason, by appropriately adjusting the refractive power and the amount of movement of the rear group BR and increasing the variable magnification division (Z / Z2) of the rear group BR, miniaturization and a sufficient zoom ratio are obtained by shortening the total length of the lens. ..

Further, as the variable magnification of the rear group BR is increased, the exit pupil of the zoom lens is shortened, the angle of incidence of the light beam on the image sensor is increased, and the image quality is deteriorated due to shading or the like. Therefore, by arranging a lens group having a positive refractive power in the vicinity of the image sensor, the incident angle is loosened and high image quality is facilitated.

Next, the features of the zoom lens of the present invention will be described. First, the first invention corresponds to Examples 1 and 2, and the first invention will be described.

The first invention comprises a first lens group B1 having a positive refractive power, a second lens group B2 having a negative refractive power, and a rear group BR having a plurality of lens groups arranged in order from the object side to the image side, and zooming. At this time, the distance between adjacent lens groups changes. The lens group on the most image side of the rear group BR has a positive refractive power, the imaging magnification of the second lens group B2 at the wide-angle end at infinity focusing is β2w, and the infinity focus of the second lens group at the telephoto end. The imaging magnification at the time of focusing is β2t.

The total length of the lens at the wide-angle end is Lw, the total length of the lens at the telephoto end is Lt, the focal length of the zoom lens at the wide-angle end is fw, the focal length of the first lens group B1 is f1, and the second lens group B2 is in focus at infinity. Let f2 be the focal length and ft be the focal length of the zoom lens at the telephoto end.

The magnification ratio of the zoom lens from the wide-angle end to the telephoto end is Z, the magnification ratio of the second lens group B2 from the wide-angle end to the telephoto end at infinity focus is Z2, and the back focus at the telephoto end is skt. .. Then, the variable ratio Z and the variable ratio Z2 are set.
Z = ft / fw
Z2 = β2t / β2w
And. At this time,
0.5 <Lw / fw <4.0 ... (1X)
-5.5 <f1 / f2 <-2.0 ... (2X)
1.7 <Z / Z2 <3.0 ... (3X)
0.0 <skt / Lt <0.2 ... (4X)
Satisfies the conditional expression.

Further, in the first invention, it is preferable that the following conditional expression is satisfied.

The distance between the second lens group B2 and the rear group BR at the wide-angle end is D2w. Let M1 be the amount of movement of the first lens group B1 in zooming from the wide-angle end to the telephoto end. Here, the amount of movement of the lens group in zooming from the wide-angle end to the telephoto end means the difference in the optical axis direction between the position of the wide-angle end and the position of the telephoto end.

The sign of the amount of movement is positive when it is located on the image side at the telephoto end compared to the wide-angle end, and negative when it is located on the object side. Let M2 be the amount of movement of the second lens group B2 in zooming from the wide-angle end to the telephoto end. Let ft be the focal length of the zoom lens at the telephoto end. Let fL be the focal length of the most image-side lens group of the rear group BR. At this time, it is preferable to satisfy one or more of the following conditional expressions.

0.1 <D2w / fw <0.5 ... (5X)
0.25 <M2 / M1 <0.80 ... (6X)
0.6 <f1 / ft <1.3 ... (7X)
1.0 <fL / fw <8.0 ... (8X)

Further, in the first invention, the rear group BR is arranged in order from the object side to the image side, the third lens group B3 having a positive refractive power, the fourth lens group B4 having a negative refractive power, and the fifth lens group having a positive refractive power. It consists of a lens group B5. Alternatively, the rear group BR is arranged in order from the object side to the image side, the third lens group B3 having a positive refractive power, the fourth lens group B4 having a positive refractive power, and the fifth lens group B5 having a negative refractive power. It consists of a sixth lens group B6 having a positive refractive power.

A part of the second lens group B2 moves during focusing. In Example 1 of the first invention, the lens group on the most image side of the rear group BR is immobile during zooming. The first lens group B1 is composed of negative lenses and positive lenses arranged in order from the object side to the image side. Next, the second invention corresponds to Examples 3 and 4, and the second invention will be described. In the second invention, a first lens group B1 having a positive refractive power, a second lens group B2 having a negative refractive power, a third lens group B3 having a negative refractive power, and a plurality of lenses arranged in order from the object side to the image side. It consists of a rear group BR having a lens group, and the distance between adjacent lens groups changes during zooming. The lens group on the most image side of the rear group BR has a positive refractive power, and the imaging magnification of the second lens group B2 at the wide-angle end is β2w, and the imaging magnification of the second lens group B2 at the telephoto end is β2t. The imaging magnification of the third lens group B3 at the wide-angle end is β3w, and the imaging magnification of the third lens group B3 at the telephoto end is β3t.

The total length of the lens at the wide-angle end is Lw, the total length of the lens at the telephoto end is Lt, the focal length of the zoom lens at the wide-angle end is fw, the focal length of the first lens group B1 is f1, and the second lens group B2 and the third lens at the wide-angle end. Let f23 be the focal length of the composition of group B3 when it is in focus at infinity.

The focal length of the zoom lens at the telephoto end is ft, the magnification ratio of the zoom lens from the wide-angle end to the telephoto end is Z, and the magnification ratio of the second lens group B2 at infinity focusing from the wide-angle end to the telephoto end is Let it be Z2. Let Z3 be the magnification ratio of the third lens group B3 when focusing at infinity from the wide-angle end to the telephoto end. The back focus at the telephoto end is skt,
Z = ft / fw
Z2 = β2t / β2w
Z3 = β3t / β3w
Z23 = Z2 x Z3
And. At this time,
0.5 <Lw / fw <4.0 ... (1Y)
-5.5 <f1 / f23 <-2.0 ... (2Y)
1.7 <Z / Z23 <3.0 ... (3Y)
0.0 <skt / Lt <0.2 ... (4Y)

Satisfies the conditional expression. Further, in the second invention, it is preferable that the following conditional expression is satisfied.

The distance between the third lens group B3 and the rear group BR at the wide-angle end is D3w. The amount of movement of the first lens group B1 in zooming from the wide-angle end to the telephoto end is M1, and the amount of movement of the second lens group B2 in zooming from the wide-angle end to the telephoto end is M2. Let ft be the focal length of the zoom lens at the telephoto end. Let fL be the focal length of the most image-side lens group of the rear group BR. At this time, it is preferable to satisfy one or more of the following conditional expressions.

0.1 <D3w / fw <0.5 ... (5Y)
0.25 <M2 / M1 <0.80 ... (6Y)
0.6 <f1 / ft <1.3 ... (7Y)
1.0 <fL / fw <8.0 ... (8Y)

Further, in the second invention, the rear group BR is arranged in order from the object side to the image side, the fourth lens group B4 having a positive refractive power, the fifth lens group B5 having a positive refractive power, and the sixth lens group B5 having a negative refractive power. It consists of a lens group B6 and a seventh lens group B7 having a positive refractive power. Alternatively, the rear group BR is composed of a fourth lens group B4 having a positive refractive power and a fifth lens group B5 having a positive refractive power arranged in order from the object side to the image side.

The third lens group B3 moves during focusing. The lens group on the most image side of the rear group BR is immobile during zooming. The first lens group B1 is composed of negative lenses and positive lenses arranged in order from the object side to the image side. In Examples 3 and 4 of the second invention, negative refraction in Examples 1 and 2 of the first invention This corresponds to a force second lens group B2 divided into a negative refractive power second lens group B2 and a negative refractive power third lens group B3. Then, in the first invention, the second lens group B2 moves during zooming. In the second invention, the second lens group B2 and the third lens group B3 move independently of each other during zooming.

Further, at the time of focusing, in the first invention, a subgroup of a part of the lens on the image side of the second lens group B2 is moved. In the second invention, the third lens group B3 is moving.

Further, the conditional expressions (1X) to (8X) according to the first invention described above correspond to the conditional expressions (1Y) to (8Y) according to the second invention, respectively, from a technical point of view. Therefore, regarding the technical meaning of each of the following conditional expressions, the conditional expressions (1X) to (8X) and the conditional expressions (1Y) to (8Y) will be described as conditional expressions (1) to (8) for convenience. That is, the conditional expressions (1) to (8) are set and described as follows.

0.5 <Lw / fw <4.0 ... (1)
-5.5 <f1 / f2 <-2.0 ... (2)
-5.5 <f1 / f23 <-2.0 ... (2)
1.7 <Z / Z2 <3.0 ... (3)
1.7 <Z / Z23 <3.0 ... (3)
0.0 <skt / Lt <0.2 ... (4)
0.1 <D2w / fw <0.5 ... (5)
0.1 <D3w / fw <0.5 ... (5)
0.25 <M2 / M1 <0.80 ... (6)
0.6 <f1 / ft <1.3 ... (7)
1.0 <fL / fw <8.0 ... (8)
The conditional expression (1) defines the ratio of the focal length of the zoom lens at the wide-angle end to the total length of the lens at the wide-angle end. In a zoom lens having a small image sensor, the focal length of the zoom lens at the wide-angle end decreases in proportion to the size of the image sensor, so that the value of the conditional expression (1) becomes large.

When the lower limit of the conditional expression (1) is exceeded, the total length of the lens at the wide-angle end becomes shorter than the focal length of the zoom lens at the wide-angle end. Therefore, the focal length of the zoom lens at the wide-angle end is shortened to widen the angle of view. Becomes difficult. Alternatively, the total length of the lens becomes too short, and the refractive power of each lens group constituting the zoom lens becomes too strong, so that it becomes difficult to satisfactorily correct the aberration.

If the upper limit of the conditional expression (1) is exceeded, the total length of the lens at the wide-angle end becomes longer than the focal length of the zoom lens at the wide-angle end, so that the zoom lens and the imaging device become large.

The conditional expression (2) defines the ratio of the focal lengths of the first lens group B1 and the second lens group B2. When the lower limit of the conditional expression (2) is exceeded, the negative refractive power of the second lens group B2 becomes too strong with respect to the positive refractive power of the first lens group B1 (the absolute value of the negative refractive power becomes large). Therefore, it becomes difficult to shorten the total length of the lens at the wide-angle end.

When the upper limit of the conditional expression (2) is exceeded, the negative refractive power of the second lens group B2 becomes too weak with respect to the positive refractive power of the first lens group B1 (the absolute value of the negative refractive power becomes small). Too). Therefore, when trying to obtain a desired zoom ratio, it becomes difficult to obtain a desired zoom ratio because the increase in the variable magnification of the rear group BR is not enough.

In the second invention, the combined focal lengths of the second lens group B2 and the third lens group B3 correspond to the conditional expression (2).

The conditional expression (3) is a conditional expression that defines the variable magnification share of the second lens group B2 with respect to the variable magnification ratio (= ft / fw) of the zoom lens. Since the variable ratio Z can be expressed by the product of the variable share Z2 of the second lens group B2 and the variable share ZBR of the rear group BR, the amount corresponding to the variable share of the rear group BR is defined.

If the lower limit of the conditional expression (3) is exceeded, the variable division of the rear group BR becomes small, and it becomes difficult to obtain a desired zoom ratio. Alternatively, since it is necessary to increase the variable magnification of the second lens group B2, the total length of the lens increases, especially at the wide-angle end, and the zoom lens becomes larger.

If the upper limit of the conditional expression (3) is exceeded, the scaling factor of the rear group BR becomes too large, so that it becomes difficult to correct coma and curvature of field, and the optical performance deteriorates.

In the second invention, the product of the variable magnification sharing of the second lens group B2 and the third lens group B3 corresponds to the conditional expression (3).

Conditional expression (4) defines the air conversion distance from the lens surface on the image side of the lens having the refractive power closest to the image side at the telephoto end to the image surface. By arranging a lens group having a positive refractive power in the vicinity of the image sensor, the angle of incidence on the image sensor is loosened to improve the image quality.

If the lower limit of the conditional expression (4) is exceeded, the lens group on the image side and the image sensor are likely to interfere with each other, which is not good.

When the upper limit value of the conditional expression (4) is exceeded, the scaling factor of the lens group on the image side becomes smaller, and it becomes difficult to increase the scaling factor of the entire rear group BR. Alternatively, it is not good because the lens group on the image side at the wide-angle end must be arranged away from the image sensor, and the total length of the lens at the wide-angle end increases.

It should be noted that, in order to realize a zoom lens having excellent sensor incident angle characteristics while being a compact, high-performance zoom lens with few aberrations, the numerical range of the conditional equations (1) to (4) is as follows. It is good to set like this.

2.5 <Lw / fw <3.8 ... (1a)
-5.0 <f1 / f2 <-3.5 ... (2a)
-5.0 <f1 / f23 <-3.5 ... (2a)
1.7 <Z / Z2 <2.5 ... (3a)
1.7 <Z / Z23 <2.5 ... (3a)
0.02 <skt / Lt <0.15 ... (4a)
More preferably, it is preferable to set the numerical range of the conditional expression (1) to the conditional expression (4) as follows.

2.7 <Lw / fw <3.7 ... (1b)
-4.8 <f1 / f2 <-4.0 ... (2b)
-4.8 <f1 / f23 <-4.0 ... (2b)
1.7 <Z / Z2 <2.2 ... (3b)
1.7 <Z / Z23 <2.2 ... (3b)
0.02 <skt / Lt <0.08 ... (4b)
The conditional expression (5) defines the relationship between the distance between the second lens group B2 (third lens group B3) and the rear group BR and the focal length of the zoom lens at the wide-angle end. When the distance between the second lens group B2 (third lens group B3) and the rear group BR becomes shorter than the focal length of the zoom lens at the wide-angle end beyond the lower limit of the conditional expression (5), the second lens group B2 (3rd lens group B3) ( The variable focal length of the third lens group B3) becomes too small. This makes it difficult to obtain the desired zoom ratio.

When the upper limit of the conditional expression (5) is exceeded, the distance between the second lens group B2 (third lens group B3) and the rear group BR becomes longer with respect to the focal length of the zoom lens at the wide-angle end, and the total length of the lens at the wide-angle end. Is not good because it becomes long.

The conditional expression (6) defines the movement amount ratio of the first lens group B1 and the second lens group B2 during zooming. When the lower limit of the conditional expression (6) is exceeded, the amount of movement of the first lens group B1 becomes large, and the total length of the lens at the telephoto end becomes long, or the total length of the lens at the wide-angle end becomes too short, so that the image plane is curved at the wide-angle end. Is difficult to correct.

If the upper limit of the conditional expression (6) is exceeded, the variable magnification of the second lens group B2 becomes too small, which makes it difficult to obtain a desired zoom ratio, or of each lens group constituting the rear group BR. Since the refractive power becomes strong, it becomes difficult to correct coma aberration and curvature of field at the telephoto end.

The conditional expression (7) defines the relationship between the focal length of the first lens group B1 and the focal length of the zoom lens at the telephoto end. If the lower limit of the conditional expression (7) is exceeded, the positive refractive power of the first lens group B1 becomes too strong, and it becomes difficult to correct spherical aberration and coma at the telephoto end.

If the upper limit of the conditional expression (7) is exceeded, the positive refractive power of the first lens group B1 becomes too weak, so that the total length of the lens at the wide-angle end becomes long.

Conditional expression (8) defines the relationship between the positive refractive power of the lens group on the most image side of the rear group BR and the focal length of the zoom lens at the wide-angle end. When the lower limit of the conditional expression (8) is exceeded, the positive refractive power of the lens group on the image side becomes too strong, and the incident angle characteristic of the light flux to the image sensor fluctuates greatly from the wide-angle end to the telephoto end, and the image quality deteriorates. Come on.

If the upper limit of the conditional expression (8) is exceeded, the positive refractive power of the lens group on the image side becomes too weak, so that the angle of incidence of the luminous flux on the image sensor becomes tight, shading occurs frequently, and the image quality deteriorates. Come on.

Even more preferably, it is preferable to set the numerical range of the conditional expressions (5) to (8) as follows.

0.20 <D2w / fw <0.49 ... (5a)
0.20 <D3w / fw <0.49 ... (5a)
0.26 <M1 / M2 <0.55 ... (6a)
0.62 <f1 / ft <1.00 ... (7a)
1.5 <fL / fw <2.7 ... (8a)
As described above, according to the present invention, it is possible to obtain a zoom lens in which the entire system is small, has high performance, has few aberrations, the incident angle of the luminous flux to the image sensor is small, and the incident angle characteristics are excellent.

Next, an embodiment of a digital still camera using a zoom lens as shown in each embodiment as a photographing optical system will be described with reference to FIG.

In FIG. 9, 20 is a camera body, and 21 is an imaging optical system composed of any of the zoom lenses described in Examples 1 to 4. Reference numeral 22 denotes an image pickup element (photoelectric conversion element) such as a CCD sensor or a CMOS sensor that is built in the camera body and receives a subject image formed by the image pickup optics 21. Reference numeral 23 denotes a memory for recording information corresponding to the subject image photoelectrically converted by the image pickup element 22. Reference numeral 24 denotes a finder composed of a liquid crystal display panel or the like and for observing a subject image formed on the image pickup device 22.

By applying the zoom lens of the present invention to an image pickup device such as a digital still camera in this way, an image pickup device having a high-magnification zoom lens while being compact and having high performance is obtained. Next, numerical data 1 to 4 corresponding to Examples 1 to 4 of the present invention are shown. In each numerical data, i indicates the order of the optical planes from the object side. ri is the radius of curvature of the i-th optical plane (i-plane), di is the distance between the i-th plane and the i + 1 plane, and ndi and νdi are the refractive indexes of the material of the i-th optical member with respect to the d-line, respectively. Shows the rate and Abbe number.

Further, when k is the eccentricity, A4, A6, A8, and A10 are the aspherical coefficients, and the displacement in the optical axis direction at the position of the height h from the optical axis is x with respect to the surface apex, the aspherical shape. Is
x = (h ² / R) / [1 + [1- (1 + k) (h / R) ² ] ^1/2 ] + A4h ⁴
+ A6h ⁶ + A8h ⁸ + A10h ¹⁰
Is displayed. However, R is the radius of curvature of the paraxial axis. Further, for example, display of "E-Z" means ^{"10 -Z".} The last two surfaces in the numerical embodiment are the surfaces of optical blocks such as filters and face plates.

In each embodiment, the back focus (BF) is the air-equivalent distance from the image-side lens surface of the image-side lens having the refractive power to the paraxial image plane. The total length of the lens is the distance from the first lens surface to the lens surface closest to the image side plus the back focus value.

Table 1 shows the correspondence between each parameter of the above-mentioned conditional expression and each conditional expression in each numerical data.

(Numerical data 1)
Surface data Surface number rd nd vd Effective diameter
1 18.123 0.60 1.95906 17.5 16.60
2 14.856 2.55 1.72916 54.1 15.55
3 130.788 (variable) 14.90
4 * 223.762 0.50 1.85135 40.1 13.80
5 * 7.615 2.54 10.80
6 -63.028 0.40 1.77250 49.6 10.60
7 42.972 0.05 10.25
8 14.214 1.40 1.94595 18.0 9.95
9 -5017.360 2.30 9.65
10 -10.202 0.40 1.69560 59.0 7.65
11 -150.405 (variable) 8.00
12 * 11.891 1.45 1.85135 40.1 8.65
13 * -52.848 0.05 8.65
14 13.959 0.40 1.92286 18.9 8.60
15 8.921 2.15 1.65160 58.5 8.35
16 -19.503 1.46 8.25
17 (Aperture) ∞ 0.50 7.55
18 24.299 0.40 2.00069 25.5 6.40
19 5.298 1.60 1.48749 70.2 5.90
20 -72.773 (variable) 5.75
21 -10.754 0.40 1.85150 40.8 7.85
22 51.790 0.66 8.75
23 31.015 2.83 2.00100 29.1 11.45
24 -10.810 3.79 11.80
25 * -4.516 0.70 1.85135 40.1 11.85
26 * -9.848 (variable) 14.55
27 33.437 3.25 2.05090 26.9 22.55
28 -98.965 1.41 22.55
29 ∞ 0.40 1.51633 64.1 25.00
30 ∞ 0.50 25.00
Image plane ∞
Aspherical data 4th surface
K = 0.00000e + 000 A 4 = -3.94851e-005 A 6 = 7.95350e-007 A 8 = -8.05182e-010
Side 5
K = -4.50508e-001 A 4 = -2.4061e-005 A 6 = -3.48107e-007 A 8 = 4.71280e-008 A10 = -2.11674e-009 A12 = 6.57505e-011
12th page
K = 0.00000e + 000 A 4 = -1.80955e-004 A 6 = 2.19074e-008 A 8 = -1.56373e-009
Page 13
K = 0.00000e + 000 A 4 = 1.50778e-004
25th page
K = -9.99877e-001 A 4 = -7.71193e-005 A 6 = 7.34673e-006 A 8 = -1.38754e-007
26th page
K = 0.00000e + 000 A 4 = 4.23391e-004
Various data Zoom ratio 2.75
Wide-angle medium telephoto focal length 12.35 18.17 33.95
F number 3.61 3.92 4.12
Half angle of view (degrees) 37.63 30.77 17.67
Image height 9.52 10.82 10.82
Total lens length 39.19 42.43 49.73
BF 2.18 2.18 2.18
d 3 0.36 1.72 5.43
d11 3.75 2.26 0.25
d20 2.03 2.47 4.49
d26 0.50 3.43 7.00


(Numerical data 2)
Surface data Surface number rd nd vd Effective diameter
1 20.133 0.60 1.95906 17.5 16.15
2 15.419 2.47 1.77250 49.6 15.30
3 198.313 (variable) 14.85
4 * 203.740 0.50 1.85135 40.1 12.55
5 * 9.348 2.06 10.55
6 -45.311 0.40 1.69560 59.0 10.35
7 31.533 0.05 9.90
8 16.679 1.38 1.94595 18.0 9.75
9 -104.526 2.36 9.45
10 -9.988 0.40 1.72916 54.7 8.05
11 -95.199 (variable) 8.50
12 * 20.400 1.30 1.85135 40.1 9.00
13 * -35.971 0.05 9.10
14 12.883 0.40 1.95906 17.5 9.25
15 10.035 2.30 1.61800 63.3 9.05
16 -20.354 0.50 8.95
17 (Aperture) ∞ 2.00 8.32
18 21.998 0.40 1.92286 18.9 7.00
19 6.121 1.63 1.51742 52.4 6.60
20 65.491 (variable) 6.95
21 -10.016 0.40 1.64769 33.8 7.55
22 29.217 0.85 8.60
23 25.389 2.43 1.92119 24.0 10.95
24 -12.704 (variable) 11.20
25 * -5.393 0.70 1.85135 40.1 11.60
26 * -11.294 (variable) 14.15
27 29.704 3.60 2.00100 29.1 22.80
28 -96.860 (variable) 22.80
29 ∞ 0.40 1.51633 64.1 25.00
30 ∞ 0.50 25.00
Image plane ∞
Aspherical data 4th surface
K = 0.00000e + 000 A 4 = -8.81229e-005 A 6 = 2.02914e-006 A 8 = -1.15994e-008
Side 5
K = 1.11065e + 000 A 4 = -3.28221e-004 A 6 = -1.90925e-006 A 8 = -1.99125e-007 A10 = 7.06974e-009 A12 = -1.85702e-010
12th page
K = 0.00000e + 000 A 4 = -1.54748e-004 A 6 = -1.57024e-007 A 8 = -2.09106e-009
Page 13
K = 0.00000e + 000 A 4 = 2.79627e-005
25th page
K = -7.41886e-001 A 4 = -1.09795e-004 A 6 = 2.81661e-006 A 8 = -9.79363e-008
26th page
K = 0.00000e + 000 A 4 = 1.45629e-004
Various data Zoom ratio 2.36
Wide-angle medium telephoto focal length 14.40 21.55 33.95
F number 2.88 3.33 3.61
Half angle of view (degrees) 33.47 26.65 17.67
Image height 9.52 10.82 10.82
Total lens length 40.12 44.17 49.73
BF 2.19 2.14 2.05
d 3 0.26 2.45 5.40
d11 3.20 1.69 0.26
d20 1.45 2.02 2.99
d24 5.65 5.64 5.48
d26 0.60 3.46 6.78
d28 1.43 1.38 1.28


(Numerical data 3)
Surface data Surface number rd nd vd Effective diameter
1 21.212 0.60 1.95906 17.5 16.25
2 16.093 2.45 1.76385 48.5 15.45
3 277.673 (variable) 15.05
4 276.769 0.50 1.88300 40.8 13.85
5 10.280 2.53 11.60
6 * -40.832 0.50 1.69350 53.2 11.40
7 * 55.879 0.05 11.10
8 18.381 1.35 1.94595 18.0 10.80
9 -338.630 (variable) 10.55
10 -10.786 0.40 1.59522 67.7 8.85
11 -199.588 (variable) 9.10
12 * 14.192 1.52 1.80139 45.5 9.75
13 * -53.657 0.05 9.75
14 12.555 0.40 1.85478 24.8 9.70
15 8.784 2.52 1.59522 67.7 9.40
16 -21.442 1.35 9.25
17 (Aperture) ∞ 0.50 8.46
18 28.449 0.40 2.00069 25.5 7.30
19 5.915 1.73 1.49700 81.5 6.70
20 89.905 (variable) 6.55
21 -10.682 0.40 1.51742 52.4 9.00
22 40.317 0.49 10.40
23 29.561 2.67 2.00100 29.1 12.10
24 -13.231 (variable) 12.35
25 * -6.141 0.70 1.85135 40.1 12.30
26 * -18.028 (variable) 14.50
27 45.603 2.45 1.88300 40.8 21.30
28 -108.791 1.41 21.40
29 ∞ 0.40 1.51633 64.1 25.00
30 ∞ 0.50 25.00
Image plane ∞
Aspherical data surface 6
K = 6.02972e + 000 A 4 = -3.26601e-005 A 6 = -1.45367e-007 A 8 = 2.34178e-009 A10 = 3.53338e-011 A12 = 6.77805e-012
7th page
K = 0.00000e + 000 A 4 = -9.08497e-005 A 6 = -2.68406e-007 A 8 = -2.77965e-008 A10 = 6.89405e-010
12th page
K = 0.00000e + 000 A 4 = -9.65946e-005 A 6 = -1.63826e-007 A 8 = -5.64763e-010
Page 13
K = 0.00000e + 000 A 4 = 1.30413e-004
25th page
K = -1.02717e + 000 A 4 = -4.40595e-005 A 6 = 1.29829e-006 A 8 = -4.44834e-009
26th page
K = 0.00000e + 000 A 4 = 1.51440e-004
Various data Zoom ratio 2.36
Wide-angle medium telephoto focal length 14.40 22.63 33.95
F number 2.88 3.24 3.61
Half angle of view (degrees) 33.47 25.55 17.67
Image height 9.52 10.82 10.82
Total lens length 40.50 44.53 49.73
BF 2.18 2.18 2.18
d 3 0.25 2.30 4.92
d 9 2.40 2.62 2.85
d11 3.90 1.74 0.25
d20 3.63 4.29 5.30
d24 4.05 3.92 3.66
d26 0.52 3.91 7.00


(Numerical data 4)
Surface data Surface number rd nd vd Effective diameter
1 34.402 0.60 1.95906 17.5 19.60
2 25.316 2.40 1.43875 94.7 19.05
3 1086.348 0.05 18.80
4 18.919 2.17 1.59282 68.6 17.60
5 90.946 (variable) 17.30
6 * 93.057 0.50 1.85135 40.1 12.55
7 * 7.998 2.58 10.10
8 -21.200 0.40 1.76385 48.5 9.80
9 182.458 0.05 9.55
10 17.812 1.20 1.98738 16.4 9.30
11 -138.565 (variable) 9.00
12 -13.051 0.40 1.69560 59.0 8.70
13 -102.791 (variable) 9.10
14 (Aperture) ∞ 0.10 9.20
15 * 9.438 2.10 1.76802 49.2 10.05
16 * -104.717 0.05 9.90
17 11.041 0.40 2.00100 29.1 9.45
18 6.341 2.50 1.53172 48.8 8.70
19 -71.860 1.64 8.45
20 16.419 2.29 1.77250 49.6 7.20
21 -5.880 0.97 2.00069 25.5 7.15
22 12.660 1.67 7.55
23 -10.306 0.45 2.00069 25.5 7.90
24 -23.844 0.05 8.75
25 22.266 2.70 1.80810 22.8 10.85
26 -11.047 0.05 11.15
27 52.596 1.15 1.66565 35.6 11.10
28 -48.247 4.00 11.05
29 * -4.710 0.70 1.85135 40.1 10.70
30 * -16.701 (variable) 13.35
31 52.499 2.58 2.05090 26.9 21.40
32 -71.681 1.41 21.55
33 ∞ 0.40 1.51633 64.1 25.00
34 ∞ 0.50 25.00
Image plane ∞
Aspherical data surface 6
K = 0.00000e + 000 A 4 = 4.56624e-007 A 6 = -1.11240e-006 A 8 = 1.46545e-008
7th page
K = -1.06087e + 000 A 4 = 2.17460e-004 A 6 = 3.33756e-007 A 8 = 2.69795e-008 A10 = -3.29115e-009 A12 = 8.50750e-011
Page 15
K = 0.00000e + 000 A 4 = -2.97893e-005 A 6 = 6.70795e-008 A 8 = 8.31492e-009
16th page
K = 0.00000e + 000 A 4 = 1.44064e-004
Page 29
K =-9.79280e-001 A 4 = -3.61265e-004 A 6 = 9.57886e-007 A 8 = 8.16187e-008
30th page
K = 0.00000e + 000 A 4 = 2.45351e-004
Various data Zoom ratio 4.10
Wide-angle medium telephoto focal length 12.35 23.05 50.59
F number 4.12 4.12 4.12
Half angle of view (degrees) 37.63 25.15 12.07
Image height 9.52 10.82 10.82
Total lens length 44.91 49.85 58.59
BF 2.18 2.18 2.18
d 5 0.25 3.92 10.24
d11 2.34 2.03 3.27
d13 5.89 3.36 0.15
d30 0.50 4.60 9.00

B1 1st lens group B2 2nd lens group B3 3rd lens group B4 4th lens group B5 5th lens group B6 6th lens group B7 7th lens group BR rear group d d line g g line ΔM meridional image plane ΔS sagittal Image plane IP Imaging plane SP Aperture GB CCD force plate, low pass filter, etc. Glass block ω Half angle of view fno F number

Claims (21)

It consists of a first lens group with a positive refractive power, a second lens group with a negative refractive power, and a rear group with a plurality of lens groups arranged in order from the object side to the image side.
In a zoom lens where the distance between adjacent lens groups changes during zooming
The lens group on the image side of the rear group has a positive refractive power and has a positive refractive power.
The imaging magnification of the second lens group at the wide-angle end at infinity focusing is β2w, and the imaging magnification of the second lens group at the telephoto end at infinity focusing is β2t.
The total length of the lens at the wide-angle end is Lw, the total length of the lens at the telephoto end is Lt, the focal length of the zoom lens at the wide-angle end is fw, the focal length of the first lens group is f1, and the second lens group is in focus at infinity. The focal length is f2, the focal length of the zoom lens at the telephoto end is ft, the magnification ratio of the zoom lens from the wide-angle end to the telephoto end is Z, and the magnification ratio of the zoom lens is Z, and the infinity of the second lens group from the wide-angle end to the telephoto end. The magnification ratio at the time of focusing is Z2, and the back focus at the telephoto end is skt.
Z = ft / fw for Z and Z2
Z2 = β2t / β2w
When
0.5 <Lw / fw <4.0
-5.5 <f1 / f2 <-2.0
1.7 <Z / Z2 <3.0
0.0 <skt / Lt <0.2
A zoom lens characterized by satisfying the conditional expression. When the distance between the second lens group and the rear group at the wide-angle end is D2w,
0.1 <D2w / fw <0.5
The zoom lens according to claim 1, wherein the zoom lens satisfies the conditional expression. The zoom lens according to claim 1 or 2, wherein the first lens group is composed of a negative lens and a positive lens arranged in order from the object side to the image side. When the amount of movement of the first lens group in zooming to the wide-angle end or the telephoto end is M1, and the amount of movement of the second lens group in zooming to the wide-angle end or the telephoto end is M2.
0.25 <M2 / M1 <0.80
The zoom lens according to any one of claims 1 to 3, wherein the zoom lens satisfies the conditional expression. When the focal length of the zoom lens at the telephoto end is ft,
0.6 <f1 / ft <1.3
The zoom lens according to any one of claims 1 to 4, wherein the zoom lens satisfies the conditional expression. When the focal length of the most image-side lens group in the rear group is fL,
1.0 <fL / fw <8.0
The zoom lens according to any one of claims 1 to 5, wherein the zoom lens satisfies the conditional expression. The rear group is characterized by consisting of a third lens group having a positive refractive power, a fourth lens group having a negative refractive power, and a fifth lens group having a positive refractive power arranged in order from the object side to the image side. The zoom lens according to any one of claims 1 to 6. The rear group is arranged in order from the object side to the image side, the third lens group having a positive refractive power, the fourth lens group having a positive refractive power, the fifth lens group having a negative refractive power, and the positive refractive power. The zoom lens according to any one of claims 1 to 6, wherein the zoom lens comprises a sixth lens group. The zoom lens according to any one of claims 1 to 8, wherein a part of the second lens group moves during focusing. The zoom lens according to any one of claims 1 to 9, wherein the lens group on the most image side of the rear group is immovable during zooming. It consists of a first lens group with a positive refractive power, a second lens group with a negative refractive power, a third lens group with a negative refractive power, and a rear group having a plurality of lens groups arranged in order from the object side to the image side. ,
In a zoom lens where the distance between adjacent lens groups changes during zooming
The lens group on the most image side of the rear group has a positive refractive power and has a positive refractive power.
The imaging magnification of the second lens group at the wide-angle end at infinity focus is β2w, the imaging magnification of the second lens group at the telephoto end at infinity focusing is β2t, and the imaging magnification of the third lens group at the wide-angle end is β2t. The magnification is β3w, and the imaging magnification of the third lens group at the telephoto end is β3t.
The total length of the lens at the wide-angle end is Lw, the total length of the lens at the telephoto end is Lt, the focal distance of the zoom lens at the wide-angle end is fw, the focal distance of the first lens group is f1, and the second lens group and the first lens group at the wide-angle end. The combined focal distance of the three lens groups at infinity is f23, the focal distance of the zoom lens at the telephoto end is ft, the magnification ratio of the zoom lens from the wide-angle end to the telephoto end is Z, and the telephoto end is telephoto. The magnification ratio of the second lens group at infinity focusing toward the end is Z2, the magnification ratio of the third lens group at infinity focusing from the wide-angle end to the telephoto end is Z3, and the back at the telephoto end. Focus on skt
Z = ft / fw
Z2 = β2t / β2w
Z3 = β3t / β3w
Z23 = Z2 x Z3
When
0.5 <Lw / fw <4.0
-5.5 <f1 / f23 <-2.0
1.7 <Z / Z23 <3.0
0.0 <skt / Lt <0.2
A zoom lens characterized by satisfying the conditional expression. When the distance between the third lens group and the rear group at the wide-angle end is D3w,
0.1 <D3w / fw <0.5
The zoom lens according to claim 11, wherein the zoom lens satisfies the conditional expression. The zoom lens according to claim 11 or 12, wherein the first lens group is composed of a negative lens and a positive lens arranged in order from the object side to the image side. When the amount of movement of the first lens group in zooming to the wide-angle end or the telephoto end is M1, and the amount of movement of the second lens group in zooming to the wide-angle end or the telephoto end is M2.
0.25 <M2 / M1 <0.80
The zoom lens according to any one of claims 11 to 13, characterized in that the conditional expression is satisfied. When the focal length of the zoom lens at the telephoto end is ft,
0.6 <f1 / ft <1.3
The zoom lens according to any one of claims 11 to 14, wherein the zoom lens satisfies the conditional expression. When the focal length of the lens group on the image side of the rear group is fL,
1.0 <fL / fw <8.0
The zoom lens according to any one of claims 11 to 15, characterized in that the conditional expression is satisfied. The rear group is arranged in order from the object side to the image side, the fourth lens group having a positive refractive power, the fifth lens group having a positive refractive power, the sixth lens group having a negative refractive power, and the positive refractive power. The zoom lens according to any one of claims 11 to 16, wherein the zoom lens comprises a seventh lens group. Any one of claims 11 to 16, wherein the rear group comprises a fourth lens group having a positive refractive power and a fifth lens group having a positive refractive power arranged in order from the object side to the image side. The zoom lens described in the section. The zoom lens according to any one of claims 11 to 18, wherein the third lens group moves during focusing. The zoom lens according to any one of claims 11 to 19, wherein the lens group on the most image side of the rear group is immovable during zooming. An image pickup apparatus comprising the zoom lens according to any one of claims 1 to 20 and an image pickup element that receives an image formed by the zoom lens.